#include <iostream>
using namespace std;

// 带有默认参数的函数声明
double Area(double radius, double pi = 3.14);

int main()
{
	// Call function
	cout << Area(4) << endl;// 忽略第二个参数，使用默认值
	cout << Area(4, 4.14) << endl;

	return 0;
}

double Area(double radius, double pi)
{
	return pi * radius * radius;
}